webr-quarto.qmd

---
title: "webR with Quarto HTML Standalone Document Proof of Concept"
subtitle: "Experiments with an Interactive Quarto Document using webR v0.1.0"
author: "James J Balamuta; modified by EEH"
repo:  https://github.com/RVerse-Tutorials/webR-quarto-demos
engine: knitr
execute:
  echo: true
  error: true
embed-resources: true
format:
    html: 
      toc: true
      code-tools:
        source: https://github.com/RVerse-Tutorials/webR-quarto-demos/blob/main/webr-quarto.qmd
      include-in-header: webr-setup.html
repo-url: https://github.com/RVerse-Tutorials/webR-quarto-demos
repo-actions: [edit, source]
editor: source
---

{{< include _webr-setup.qmd >}}

# Background

This is not my work. Forked from and go there to see how this works
James J Balamuta: <https://github.com/coatless-r-n-d/webR-quarto-demos>

This was created by JJB to explore how [WebR](https://docs.r-wasm.org/webr/latest/) can be embedded in a Quarto Document for the purposes of teaching _R_. 


## Setup 

The yaml includes this. Note the `webr-setup.html` and _webr-setup.qmd` files.
```
---
title: "the title"
engine: knitr
execute:
  echo: true
  error: true
embed-resources: true
format:
    html: 
      toc: true
      include-in-header: webr-setup.html
editor: source
---

{{< include _webr-setup.qmd >}}
```

## Calling WebR

Use `{webr}` rather than `{r}` for your code.

### Linear Regression

We'll first start with the WebR team's demo example or the statistician way of
saying, "Hello world!"... Aka linear regression:

```{webr}
fit = lm(mpg ~ am, data=mtcars)
summary(fit)
```

### Retrieving prior objects

Each WebR cell appears to be connected to each other. Thus, we can access the
`fit` outcome:

```{webr}
coef(fit)
```

```{webr}
anova(fit)
```

### Mixing active and non-active _R_ code

```{webr}
# Let's classify 
temperature = 60
```


```{webr}
if (temperature > 76) {
    print("Hot!")
} else {
    print("Cold!")
}
```


### Summarize Data

Glancing at data frames yields: 

```{webr}
summary(mtcars)
```

### Errors and Warnings


```{webr}
stop("What happens if an error is present?")
```

```{webr}
warning("You shouldn't be here...")
```


### Base graphics

Graphing with base R 

```{webr}
plot(pressure)
```

More advanced base R graphing... 

```{webr}
x1 = seq(0, 1, length = 20)
y1 = rep(0, 20)
x2 = rep(0, 20)
y2 = seq(0.75, 0, length = 20)

plot(0, type = "n",
     axes = FALSE, ylab = "", xlab = "", 
     xlim = c(0, 1), ylim = c(0, 0.75), asp = 1,
     main = "Straight Lines as a Curve")

segments(x1, y1, x2, y2)
box(col = "grey")
```

### ggplot2 Graphics

There is an extra step of installing packages that are not part of the base.

CLICK RUN AND WAIT LIKE 1 MINUTE. When you see output, it means it is loaded. Be patient.

```{webr}
# Install non-base R packages
webr::install("ggplot2")
```

Now we can use ggplot2 in the qmd.
```{webr}
library("ggplot2")
p = ggplot(mpg, aes(class, hwy))
p + geom_boxplot()
```